Influence of partial replacement of fish meal and fish oil with vegetable products on the growth and muscle cellularity of juvenile shi drum, Umbrina cirrosa

Seven-month-old shi drum (Umbrina cirrosa) specimens (mean weight 18.98 g, mean length 11.80 cm) were classified into 2 groups, a control group (C) fed a standard diet and a vegetal group (V) fed a diet with partial replacement of fish meal and fish oil by vegetable products. The body and muscle parameters were studied on days 0, 27, and 62 of the experiment. On day 27, body length was similar in both groups, but body weight was significantly lower in group V than in group C. The transverse area of the white muscle was also significantly lower in V than in C. Hypertrophy was higher in C than in V, whereas hyperplasia was higher in V than in C. On day 62, the body parameters showed similar results to those found on day 27. Muscle cellularity was different from that found on day 27, since hypertrophy was higher in V than in C and hyperplasia was higher in C than in V. The feed conversion rate and specific growth rate were similar in both groups, but the daily intake rate was lower in V than in C. Therefore, it seems that the percentage of vegetables in the vegetal feed was excessively high and this caused less acceptance by the fish. The hepatosomatic, viscerosomatic, and intestinal length indices were similar in both groups. Survival was nearly 100% in both groups.Verrugatos (Umbrina cirrosa) de 7 meses (peso medio de 18.98 g, longitud media de 11.80 cm) fueron clasificados en 2 grupos: un grupo control (C), que fue alimentado con una dieta estándar, y un grupo vegetal (V), que fue alimentado con una dieta con reemplazo parcial de harina y aceite de pescado por productos vegetales. Los parámetros corporales y musculares se estudiaron en los días 0, 27 y 62 del experimento. En el día 27, la longitud corporal fue similar en ambos grupos, pero el peso fue significativamente menor en el grupo V que en el C. El área transversa del músculo blanco fue significativamente menor en V que en C. La hipertrofia fue mayor en C que en V, mientras que la hiperplasia fue mayor en V que en C. En el día 62, los parámetros corporales mostraron resultados similares a los encontrados en el día 27. La celularidad muscular fue diferente a la encontrada en el día 27, de manera que la hipertrofia fue mayor en V que en C y la hiperplasia fue mayor en C que en V. La tasa de conversión de alimento y la tasa específica de crecimiento fueron similares en ambos grupos, pero la tasa diaria de alimentación fue menor en V que en C. Así, parece ser que el porcentaje de vegetales en la dieta vegetal fue excesivamente alto y ello causó menor aceptación por los peces. Los índices hepatosomáticos, digestosómaticos e intestinales fueron similares en ambos grupos. La supervivencia fue próxima al 100% en ambos grupos.Versión del editor0,45

Shi drum (Umbrina cirrosa) juveniles are susceptible to all Nodavirus genotypes

Nervous necrosis virus (NNV; family Nodaviridae, genus Betanodavirus) is the causative agent of viral retinopathy and encephalopathy (VER) disease, which mainly affects the larval and juvenile stages of fish. The virus has an acute lethal effect in larval stages and juveniles. According to the RNA2 sequence, NNV are mainly divided into four genotypes: RGNNV, SJNNV, BFNNV and TPNNV. The shi drum (Umbrina cirrosa) is a serious candidate for the diversification of Mediterranean aquaculture. Although aspects related to nutrition or reproduction have been elucidated others related to pathology or immunity have been poorly studied. In this regard, the shi drum is a susceptible species for betanodavirus (RGNNV) infection, as several natural outbreaks have been reported. In order to expand the actual knowledge and understand the shi drum-NNV interactions we evaluated whether this fish species is susceptible to all the NNV genotypes. Our data demonstrate that the laboratory infections with all the NNV genotypes produced clinical signs of the VER disease and mortalities in shi drum juveniles. Interestingly, clinical signs and histopathological lesions in the brain and retina were different depending on the genotype used. Finally, viral capsid protein was immunodetected in the brain and retina from all infected fish whilst infective particles were only recovered from RGNNV-, BFNNV- and TPNNV-infected specimens. In conclusion, this work demonstrates that shi drum juveniles are susceptible to all four genotypes of NNV and represent the first step in studying host–NNV interactions and immune responses in this species, which should be further characterized

The influence of organic versus conventional feeding on the growth and survival of gilthead sea bream Sparus aurata L. juveniles

Sparus aurata specimens of 11 months of age (mean weight: 90.2 g, mean length: 18.3 cm) were classified in two diet groups: one control group was fed with conventional diet, and one experimental group was fed with an organic diet. The body and muscle parameters were studied at 0, 41 and 71 days of the experiment. The results showed the highest values of body length and weight as well as the best biological feed conversion rates in the organic group. The transverse area of white muscle, the hyperplasia and the muscle fibres density were also higher in the organic than in the conventional group (P>0.05). In contrast, hypertrophy was greater in the conventional than in the organic group (P<0.05). Survival was 100% in both groups. In conclusion, the organic feeding regime was more favourable for growth than conventional feeding.Versión del edito

Effects of oral administration of 17α-ethynylestradiol on male seabream Sparus aurata L.

The effects of 17α-ethynylestradiol (EE2) on immature and mature males of the gilthead seabream (Sparus aurata L.) were studied. Gilthead seabream specimens were fed for 1 month with diets containing EE2 (5, 50, 125, 200 μg/g food). EE2 exposure altered the appetite, survival and digestive system in immature fish, and caused changes in the gonadal development, growth, survival, and some somatic indexes in mature males. The highest EE2 doses showed acute toxic effects (50% mortality) and liver injury. Gonad size was also drastically reduced

Profile of Innate Immunity in Gilthead Seabream Larvae Reflects Mortality upon Betanodavirus Reassortant Infection and Replication

Historically, gilthead seabream (Sparus aurata) has been considered a fish species resistant to nervous necrosis virus (NNV) disease. Nevertheless, mortality in seabream hatcheries, associated with typical clinical signs of the viral encephalopathy and retinopathy (VER) disease has been confirmed to be caused by RGNNV/SJNNV reassortants. Because of this, seabream larvae at 37 and 86 days post-hatching (dph) were infected by immersion with RGNNV/SJNNV and SJNNV/RGNNV reassortants under laboratory conditions, and mortality, viral replication and immunity were evaluated. Our results show that gilthead seabream larvae, mainly those at 37 dph, are susceptible to infection with both NNV reassortant genotypes, with the highest impact from the RGNNV/SJNNV reassortant. In addition, viral replication occurs at both ages (37 and 86 dph) but the recovery of infective particles was only confirmed in 37 dph larvae,; this value was also highest with the RGNNV/SJNNV reassortant. Larvae immunity, including the expression of antiviral, inflammatory and cell-mediated cytotoxicity genes, was affected by NNV infection. Levels of the natural killer lysin (Nkl) peptide were increased in SJNNV/RGNNV-infected larvae of 37 dph, though hepcidin was not. Our results demonstrate that the seabream larvae are susceptible to both NNV reassortants, though mainly to RGNNV/SJNNV, in an age-dependent manner.Versión del editor2,46

Identification of an interferon-stimulated gene, isg15, involved in host immune defense against viral infections in gilthead seabream (Sparus aurata L.)

Interferons (IFNs) play a key role in the innate immunity of vertebrates against viral infections by inducing hundreds of IFN-stimulated genes (ISGs), such as isg15. Isg15 is an ubiquitin-like protein, which can conjugate cellular and viral proteins in a process called ISGylation, although it can also act as a cytokine-like protein. Gilthead seabream (Sparus aurata L.) is an important asymptomatic carrier of viral haemorrhagic septicaemia virus (VHSV) and nodavirus, representing a threat to other co-cultivated susceptible species. In order to better understand virus-host interactions in this fish species, this study addresses the identification and molecular characterization of seabream isg15 (sb-isg15). In addition, the modulation of transcript levels of sb-isg15 was analysed in SAF-1 cells and seabream acidophilic granulocytes (AGs) stimulated in vitro with different pathogenassociated molecular patterns (PAMPs) or inoculated with VHSV and striped jack nervous necrosis virus (SJNNV). The full-length cDNA of sb-isg15 gene, encoding a predicted protein of 155 amino acids, was identified and seen to share the same characteristics as other fish and mammalian isg15 genes. Here we report the clear induction of sb-isg15 transcript levels in SAF-1 cells and AGs stimulated with toll-like receptor (TLR) ligands, such as polyinosinic:polycytidylic acid (poly I:C) or genomic DNA from Vibrio anguillarum (VaDNA), respectively. Furthermore, VHSV and SJNNV inoculation induced a significant degree of sb-isg15 transcription in SAF-1 cells and AGs. However, the relative levels of viral RNA transcription showed that SJNNV replication seems to be more efficient than VHSV in both in vitro systems. Interestingly, sb-isg15 transcript induction elicited by VaDNA was reduced in VHSV- and SJNNV-inoculated AGs, suggesting an interference prompted by the viruses against the type I IFN system. Taken together, these findings support the use of seabream AGs as a valuable experimental system to study virus-host interactions, in which sb-isg15 seems to play an important role.Versión del edito

Long-term Effects of the Larval Photoperiod on the Subsequent Growth of Shi Drum Umbrina cirrosa L. Specimens and the Fillet Texture at Commercial Size

Three groups of shi drum Umbrina cirrosa L. were reared with different photoperiod regimes: 24L, 12L:12D and 16L:8D (natural photoperiod) during the larval period and then all of them were transferred to a natural photoperiod. At 11.8 and 20 months of age, the body growth and the muscle parameters reached the highest values in the 24L and 12L:12D groups. The 16L:8D group showed the lowest growth. When comparing 24L with 12L:12D, the highest number of white fibres was found in the 24L group, whereas the greatest fibres size was reached in the 12L:12D group. Commercial size (28-30 cm; 290-340 g) was reached at 20 months of age in the 24L and 12L:12D groups, but at 23 months in the 16L:8D group. When comparing the three groups at the commercial stage, the larval photoperiod effect was still observed, such that the highest fibres number was again found in the 24L group, whereas the greatest fibres size was reached in the 12L:12D group. The highest values of textural hardness were observed in the 16L:8D and 24L groups. A nutritional analysis was carried out in the 16L:8D group, which showed the following percentage values: 2.66, 21.2, 74.4, and 1.46 of fat, protein, moisture and ash, respectively.0,591